/Engine/Source/Runtime/Experimental/Chaos/Public/Chaos/PBDRigidClustering.h
GetActiveClusterIndex Get the current childs active cluster. Returns INDEX_NONE if not active or driven.
[FPBDRigidParticleHandle](API\Runtime\Chaos\Chaos\FPBDRigidParticleHandle) * GetActiveClusterIndex ( [FPBDRigidParticleHandle](API\Runtime\Chaos\Chaos\FPBDRigidParticleHandle) * Child )